EPR methods and systems

Abstract

Various systems and methods for detecting electron spins using electron paramagnetic resonance are described. An excitation signal generator configured to generate an excitation signal of varying amplitude and phase as compared to a reference signal may be present. A crossed-loop resonator configured to isolate a detection signal produced by the excitation signal exciting an object with a magnetic field may also be present. Further, a detection device configured to detect electron spins of the object using the detection signal isolated by the crossed-loop resonator may be present.

What is claimed is: 
     
       1. A system for detecting electron spins using electron paramagnetic resonance, the system comprising:
 an excitation signal generator configured to generate a polyphase continuous excitation signal that is not a pulsed signal; 
 a crossed-loop resonator configured to excite an object with the polyphase continuous excitation signal and isolate a detection signal produced by the excitation of the object; and 
 a detection device configured to detect electron spins of the object using the detection signal isolated by the crossed-loop resonator. 
 
     
     
       2. The system according to  claim 1 , wherein the crossed-loop resonator comprises an excitation chamber and a detection chamber, wherein the excitation signal is applied to the object disposed within the excitation chamber, and the detection signal is isolated within the detection chamber. 
     
     
       3. The system according to  claim 1 , wherein the excitation signal may be adjusted using a frank sequence, and the method further comprises cross-correlating the detection signal with the Frank sequence. 
     
     
       4. The system according to  claim 1 , wherein the power level of the excitation signal is less than 50 Watts. 
     
     
       5. The system according to  claim 1 , wherein the power level of the continuous wave excitation signal is inversely proportional to the resonator efficiency to yield B 1  sufficient for turning angles of 90°/n. 
     
     
       6. A system for detecting electron spins using electron paramagnetic resonance, the system comprising:
 an excitation signal generator configured to generate a saw-tooth shaped continuous excitation signal that is not a pulsed signal; 
 a crossed-loop resonator configured to isolate a detection signal produced by the saw tooth shaped excitation signal exciting an object in a magnetic field; and 
 a detection device configured to detect electron spins of the object using the detection signal isolated by the crossed-loop resonator. 
 
     
     
       7. The system according to  claim 6 , wherein the crossed-loop resonator comprises an excitation chamber and a detection chamber, wherein the excitation signal is applied to the object disposed within the excitation chamber, and the detection signal is isolated within the detection chamber. 
     
     
       8. The system according to  claim 6 , wherein the excitation signal may be adjusted using a frank sequence, and the method further comprises cross-correlating the detection signal with the Frank sequence. 
     
     
       9. The system according to  claim 6 , wherein the power level of the excitation signal is less than 50 Watts. 
     
     
       10. The system according to  claim 6 , wherein the power level of the continuous wave excitation signal is inversely proportional to the resonator efficiency to yield B 1  sufficient for turning angles of 90°/n. 
     
     
       11. A system for detecting electron spins using electron paramagnetic resonance, the system comprising:
 an excitation signal generator configured to generate either or both fast frequency scan excitation signals and monotonic excitation signals that are not pulsed; 
 a crossed-loop resonator configured to isolate a detection signal produced by the excitation signal exciting an object in a magnetic field; and 
 a detection device configured to detect electron spins of the object using the detection signal isolated by the crossed-loop resonator. 
 
     
     
       12. A system for detecting electron spins using electron paramagnetic resonance, the system comprising:
 a digital arbitrary wave form generator configured to generate continuous triangular-shaped excitation signals that are not pulsed; 
 a crossed-loop resonator configured to isolate a detection signal induced by the triangular-shaped excitation signal exciting an object in a magnetic field; and 
 a detection device configured to detect electron spins of the object using the detection signal isolated by the crossed-loop resonator, wherein the detection device includes a high speed digitizer and a processor. 
 
     
     
       13. A method for detecting electron spins using electron paramagnetic resonance, the method comprising:
 generating a continuous excitation signal that is not pulsed selected from the list consisting of: a saw-tooth continuous excitation signal, a fast frequency scan excitation signal, a triangular-shaped excitation signal, and a monotonic excitation signals; 
 applying the continuous excitation signal to an object located within a crossed-loop resonator; 
 isolating, using an isolation device, a detected signal received from the object when excited by the continuous signal, the detected signal being detected using a detection device configured to detect electron spins of the object; and 
 determining a finite impulse decay of the object from the detected signal. 
 
     
     
       14. The method according to  claim 13 , wherein the continuous excitation signal induces a change in energy levels of free electrons within the object. 
     
     
       15. The method according to  claim 13 , wherein the isolation device comprises a crossed-loop resonator configured to isolate the detected signal produced by the continuous excitation signal when excited with the polyphase continuous signal. 
     
     
       16. The method according to  claim 13 , wherein the excitation signal may be adjusted using a frank sequence, and the method further comprises cross-correlating the detection signal with the Frank sequence. 
     
     
       17. The method according to  claim 13 , wherein the power level of the excitation signal is less than 50 Watts. 
     
     
       18. The method according to  claim 13 , wherein the power level of the continuous wave excitation signal is inversely proportional to the resonator efficiency to yield B 1  sufficient for turning angles of 90°/n.